The present invention relates to a fuel injection valve.
German Published Patent Application No. 44 08 875 (see FIG. 1) describe a fuel injection valve which has a spherical valve closure element that coacts with a flat valve seating surface of a valve seat element. A perforated spray disk is immovably joined to the valve seat element, on its downstream end face, by way of a weld seam. This valve seat part, comprising the perforated spray disk and valve seat element, is sealedly mounted in a valve seat support. The immovable join between the valve seat part and the valve seat support is accomplished at a retaining rim of the perforated spray disk, which is under radial stress, with a circumferential weld seam.
German Patent No. 41 25 155, is a fuel injection valve in which at least one spray orifice is already provided in the valve seat element. The cylindrical valve seat element is therefore immovably joined to the valve seat support not by way of a perforated spray disk, but rather directly at its outer circumference by way of a circumferential weld seam.
U.S. Pat. No. 4,946,107 has already disclosed an electromagnetically actuable fuel injection valve that has, inter alia, a nonmagnetic thin-walled sleeve as joining element between a core and a valve seat element. The sleeve is immovably joined at its two axial ends to the core and to the valve seat element, so that the sleeve acts as valve seat support for the valve seat element. The core and the valve seat element are configured with an outside diameter such that they protrude into the sleeve at the two ends, so that the sleeve completely surrounds the two components (core and valve seat element) in these inwardly protruding regions. The immovable joins of the sleeve to the core and to the valve seat element are achieved, for example, by press-fitting. There exists, in this context, the risk that the join region will not remain completely hydraulically sealed after press-fitting or over the operating life of the injection valve.
The fuel injection valves according to the present invention have the advantage of a simple and economical manner of achieving complete hydraulic sealing between a valve seat element and a valve seat support that receives the valve seat element.
It is particularly advantageous in this context that it is possible to dispense with any joining method which requires the application of heat, such as laser welding, which disadvantageously can degrade the highly accurate dimensional tolerances in the sealing region.
Since the coating is applied on the outer enveloping surface of the easy-to-handle valve seat element, production of the coating is an easy and dependable process. The quality of the coatings that are to be applied can moreover be easily monitored.